Telecommunications systems, cable television systems, and data communication networks use optical networks to rapidly convey large amounts of information between remote points. In an optical network, information is conveyed in the form of optical signals through optical fibers. Optical fibers comprise thin strands of glass capable of transmitting the signals over long distances with very little loss. The optical signals have at least one characteristic modulated to encode audio, video, textual, real-time, non-real-time, and/or other suitable data.
For an intensity modulated differential phase shift keying (IMDPSK) system, the transmitter is a phase modulator that transmits a differentially encoded binary data signal by modulating the phase of the carrier signal. The phase modulated signal is further modulated by a bit synchronous sinusoidal clock signal. At the receiver, the encoded signal is differentially decoded and detected.